Coffee and sleep: what time should you stop drinking coffee?

How caffeine works

Caffeine does not give you energy, it masks tiredness.

To understand the link between coffee and sleep, you have to talk about one molecule: adenosine. It builds up in the brain throughout the day, the longer you stay awake. The more there is, the higher your sleep pressure. It is what makes you yawn in the evening.

Caffeine has a shape similar to adenosine. It binds to the same receptors without activating them, and blocks them. The tiredness signal is still there, but it is no longer heard. You feel more alert, while your need for sleep has not changed.

Two things follow from this. First, as long as there is caffeine in your blood, falling asleep is harder, because the sleep signal is scrambled. Second, when the caffeine wears off, all the built-up adenosine hits you at once: the famous slump, which often prompts another coffee. Read also: Coffee before a workout: good idea or not?.

That is what the cut-off time is all about: giving your body time to clear the caffeine before lights out. It takes much longer than you might think.

Caffeine's half-life

Five hours to clear half of it.

After a coffee, caffeine reaches the blood within about thirty minutes to an hour. Then the liver clears it slowly. The time it takes to clear half of it is called the half-life: around five hours on average in adults, with big differences from one person to another, from about two to more than eight hours.

In practice, half of your 4 pm coffee is still in your blood at 9 pm. And a quarter is still there at around 2 am. Here is what remains, in theory, of an 80 mg espresso at 11 pm, depending on when you drank it.

A simplified calculation, for a five-hour half-life and a single espresso. If you drink several coffees, the leftovers add up. If your half-life is longer, the figures are higher.

This table explains why the morning coffee almost never causes problems, and why the 5 pm one so often does. It also shows the value of a lower-caffeine drink in the afternoon: a cup of Brainstoorm at 20 mg, drunk at 4 pm, leaves about 8 mg at 11 pm by the same calculation, compared with 30 mg for the espresso.

Why we are all different

The same coffee, not the same night.

You probably know someone who drinks an espresso after dinner and sleeps like a baby, and someone else who does not sleep a wink after a coffee at 3 pm. Neither is exaggerating. Sensitivity to caffeine varies enormously, for well-understood reasons.

Age matters too: older people are generally more sensitive to caffeine's effects on sleep. Finally, some medicines slow its clearance. Talk to your doctor or pharmacist if needed.

Your cut-off time

Coffee and sleep: what time should you stop caffeine?

Combining caffeine's half-life with the studies gives a simple rule to remember: no regular coffee in the 8 to 9 hours before bed. For most people, that means having their last coffee in the early afternoon.

A benchmark for one cup of regular coffee. If you are sensitive, pregnant, on the pill or sleeping badly, bring the cut-off forward. A stronger drink, such as an energy drink, needs more margin.

Some people can drink a coffee at 4 pm with no visible effect; others will need to stop at midday. The most reliable approach is to test: bring your last coffee forward by two hours for a week, and watch how you fall asleep and whether you wake in the night.

If you work nights or irregular shifts, work back from when you actually go to bed, not from the time of day. The principle is the same: no caffeine in the hours before you need to sleep.

What changes during the night

You sleep, but less well.

Many people say: "Coffee doesn't stop me sleeping." Sometimes that is true for falling asleep. But caffeine also affects the quality of the night, and that is where the studies are most telling.

• Falling asleep takes longer, even when you do not notice.
• The night is shorter, because you fall asleep later or wake earlier.
• Deep sleep, the most restorative kind, decreases.
• Micro-awakenings are more frequent, and sleep is lighter.
• On waking, the night feels less restorative, which prompts more coffee.

The most interesting finding of the Drake study is this: with caffeine taken six hours before bed, the recordings showed a markedly shorter night, while the participants did not rate it as much worse. So you can sleep badly because of coffee without realising it.

Habit does not fully protect you. Heavy coffee drinkers build tolerance to some effects, such as feeling wired, but studies still see effects on sleep in regular drinkers.

Hidden sources

Caffeine does not only come from coffee.

Stopping coffee at 2 pm does not help much if you have a fizzy drink at 6 pm or black tea after dinner. Here are EFSA's benchmarks for the main sources of caffeine.

EFSA benchmarks (2015), except Brainstoorm, whose dose is set by the recipe. Actual content varies by product and preparation.

Think about green tea and maté too, which contain caffeine, and some pain or cold medicines, which sometimes include it. The leaflet will say. As for evening herbal teas, chamomile, verbena and lime blossom contain none.

Decaf in the evening

Decaf coffee and sleep: the right compromise?

Decaf is the most obvious way to keep the taste of coffee in the evening. It contains very little caffeine: decaffeinated roasted coffee must not contain more than 0.1%, a small amount, but not zero. Analyses have found a few milligrams per cup in most of the decaf coffees tested. To find out more, discover our mushroom coffee.

For the vast majority of people, a cup of decaf after dinner makes no difference to the night. Things can be different if you drink several large cups, or if you are particularly sensitive. In that case, chicory, roasted and naturally caffeine-free, can take over.

For more ideas for caffeine-free or low-caffeine drinks, our guide what to drink instead of coffee runs through the alternatives.

The vicious circle

Bad night, more coffee, another bad night.

This is the most common trap, and it sets in quietly. A slightly short night, an extra coffee in the morning to get through. The afternoon slump arrives, another coffee to get past it. In the evening, the caffeine is still there, falling asleep drags on, the night is short. And the next day, it starts all over again.

Stress often keeps the loop going. A racing mind in the evening, on top of afternoon caffeine, makes falling asleep even harder. Our article on how to lower cortisol offers some ideas for that side of things.

To break the circle, there is no need to give everything up. Often it is enough to change the afternoon coffee, the one that does the most damage to the night. That is exactly what several of our customers describe after switching to Brainstoorm, with 20 mg of caffeine per cup instead of about 80 mg.

Trustpilot reviews of Brainstoorm, quoted as written and translated from French. Mush n Go is rated 4.8/5 on Trustpilot, with more than 50,000 customers.

The routine

A day designed for good sleep.

Here is a sample day for someone who goes to bed around 11 pm. It keeps coffee where it is most useful, and replaces it where it harms the night.

To find out more about evening ingredients, see our pages on reishi, valerian, melatonin and magnesium bisglycinate. And if you are wondering which mushroom to choose for your nights, our comparison of the best mushroom for sleep sets it out.

Cutting down without suffering

Bring your last coffee forward in three steps.

Going from a coffee at 5 pm to a last coffee at 2 pm overnight can be tough, especially if you drink a lot. The headaches and fatigue of stopping too abruptly make many people give up. It is better to go gradually.

Who it is for

Rethinking your cut-off time is worthwhile if…

• You take more than half an hour to fall asleep, for no obvious reason.
• You still drink a regular coffee after 3 pm.
• You wake in the night, or very early in the morning, and cannot get back to sleep.
• You need a coffee to feel awake, then another to get through the afternoon.
• You are pregnant, on the pill, or have recently stopped smoking.

If you want a complete routine for the evening, the Relaxation Pack brings together Anti-Stress and Sleep+. And to understand the role of mushrooms in rest, read our guide mushrooms, adaptogenic plants and sleep.

Sources

1. Drake C., Roehrs T., Shambroom J., Roth T. (2013). Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine, 9(11).
2. Burke T. M. et al. (2015). Effects of caffeine on the human circadian clock in vivo and in vitro. Science Translational Medicine, 7(305).
3. Clark I., Landolt H. P. (2017). Coffee, caffeine, and sleep: a systematic review of epidemiological studies and randomized controlled trials. Sleep Medicine Reviews, 31.
4. Gardiner C. et al. (2023). The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews, 69.
5. EFSA NDA Panel (2015). Scientific opinion on the safety of caffeine. EFSA Journal, 13(5):4102.

Keep reading

Go further.

Coffee is only one piece of sleep. Discover our other guides, or our formula Sleep+.